The present invention relates to a circuit board for liquid crystal display, a circuit module, a liquid crystal display device using them, and a method for producing the same.
A liquid crystal display device is generally configured such that the device has a liquid crystal panel in which a liquid crystal material is held between two opposing boards, a circuit section for driving the liquid crystal panel, and a lighting device disposed behind the above-mentioned liquid crystal panel. The above-mentioned circuit section, for example in an active-type liquid crystal display device, comprises a TCP (tape carrier package) carrying a drive LSI for a source or a gate for inputting a signal from a source electrode wiring or a gate electrode wiring on the periphery of the liquid crystal panel and driving a TFT (thin film transistor) contained in the above-mentioned liquid crystal panel, and a bus board for supplying a source voltage, a ground voltage and a video signal to the TCP.
FIG. 12 is a sectional view showing a circuit section of a conventional liquid crystal display device, wherein numeral 1 designates a liquid crystal panel; numeral 2, a TFT board in which a TFT of the liquid crystal panel 1, and a gate electrode wiring and a source electrode wiring of the TFT are formed and which has wiring terminals connected to the above-mentioned gate electrode wiring and source electrode wiring on the periphery thereof; numeral 3, a color filter board; numeral 4, a drive LSI; numeral 5, a TCP which carries the drive LSI and has an input terminal and an output terminal; numeral 6, a bus board: numeral 7, a lighting device provided behind the liquid crystal panel 1; numeral 8, an outer casing frame; numeral 9, an anisotropy conductive film; and numeral 10, a connecting member.
The output terminal of the TCP 5 carrying one drive LSI 4 is connected through the anisotropy conductive film 9 to the wiring terminal of the TFT board, while the input terminal of the TCP 5 is connected through the connecting member 10 to the bus board 6.
In the above-mentioned manner, the TCP 5 and the bus board 6 connected through the anisotropy conductive film 9 to the liquid crystal panel 1 are disposed horizontally to the plane of the liquid crystal panel 1, provided with the lighting device 7 behind the liquid crystal panel 1, and covered with the outer casing frame 8.
FIG. 13 shows a configuration in which the TCP 5 connected to the liquid crystal panel 1 is bent in a manner to surround the lighting device 7 by utilizing the flexibility of the TCP 5 so that the LSI 4 and the bus board 6 are disposed behind the lighting device 7.
In the configuration of. FIGS. 12 and 13, a method of connecting the output terminal of the TCP 5 to the wiring terminal formed on the TFT panel 2 of the liquid crystal panel 1 is performed by a method of positioning one by one a plurality of TCPs 5 punched from a reel-shaped tape carrier on the wiring terminal of the TFT board 2 and then heating and pressurizing the anisotropy conductive film 9 previously and temporarily pressure bonded to the wiring terminal of the TFT board 2 or the output terminal of the TCP 5.
Also, the input terminal of the TCP 5 and the bus board 6 are connected to each other by means of a solder reflow technique, soldering or the anisotropy conductive film 9.
In the configuration of FIGS. 12 and 13, the drive LSI 4 is connected one by one to the liquid crystal panel 1, while FIG. 14 is a sectional view of a liquid crystal display device in which a plurality of drive LSIs 4 are simultaneously connected to the liquid crystal panel 1. In FIG. 14, numeral 1 designates a liquid crystal panel; numeral 11, a drive circuit module for driving the liquid crystal panel 1; numeral 12, a flexible connecting member having a width of one side of the liquid crystal panel, such as a heat seal formed of a polyester resin connecting an output terminal of the drive circuit module to a wiring terminal of the TFT board 2; numeral 7, a lighting device provided behind the liquid crystal panel 1; and numeral 8, an outer casing frame; wherein the drive circuit module 11 carries a plurality of drive LSIs 4 for a source or a gate on a circuit board 13, and the drive circuit module 11 is disposed on one side of or behind the lighting device 7 by utilizing a flexibility of the flexible connecting member 12.
In the liquid crystal display device showing in FIG. 14, a plurality of drive LSIs 4 are installed by means of a flip chip or a wire bonding technique on the circuit board 13 in which a circuit is formed on a board formed of an inorganic material, an organic material or a metal to form the drive circuit module 11; an input terminal of the flexible connecting member 12 is positioned to be aligned, thereby connecting to an output terminal of the circuit board 14; an output terminal of the flexible connecting member 12 is positioned to be aligned, thereby connecting by means of a thermal pressure bonding and the like to the wiring terminal of the TFT board 2; and a plurality of drive LSIs 4 are simultaneously connected to reduce manhour.
As described above, the conventional liquid crystal display device has had disadvantages that the TCP 5 and the bus board 6 are disposed in the direction horizontal to the liquid crystal panel 1 or behind the lighting device 7, whereby a frame portion of the outer periphery of the liquid crystal display device or widthwise size thereof becomes large, and that the drive LSIs 4 are one by one connected to the liquid crystal panel 1, thereby increasing the number of manhours.
Also, a method of forming the drive circuit module 11 carrying a plurality of drive LSIs 4 and at the same time, connecting a plurality of drive LSIs 4 to the liquid crystal panel 1, thereby increasing the number of manhours has had a disadvantage that unlike that of positioning to be aligned in the output terminal of individual TCPs 5 with a part of the wiring terminal, the output terminal of the flexible connecting member 12 is required to be connected to one side of the output terminal of the circuit board 13 and also to one side of the wiring terminal, so that the flexible connecting member 12 when thermally pressure bonded expands to cause a deviation in the pitch between terminals to become large.
An object of the present invention is to solve the above-mentioned problems, and to provide a drive circuit module for liquid crystal display device which is bendable and has a high productivity without developing a deviation in the pitch between terminals, provide a compact liquid crystal display device which uses the drive circuit module and is small in outer periphery size and thin in outer shape thickness, and provide a method of manufacturing the same.